Foch Final Acid High

Herman Krug wrote in message

Herman - You can do lots to lower acid in Foch or other high acid grapes. 1. Amelioration - Foch has lots of flavor and color. You could dilute the juice with water, say 10% and still make a nice wine. This would have reduced the 9.2 acid to about 8.3 grams-liter. It's not a direct reduction because the added water makes potbuttium bitartrate more soluble in the finished wine.

2. Cold soaking before fermentation - An example from my 2005 Vignoles. The starting acid was 9.5 grams-liter. I cold soaked the must for 3 days at about 30F. This dropped a lot of acid and the must tested at 8 grams-liter before fermentation, a 15.8% reduction.

3. Malo-Lactic fermentation after yeast fermentation is complete - An example from my 2005 Chambourcin. The starting acid was 9.7 grams-liter. After yeast fermentation and ML (followed by further cold conditioning) was complete the wine tested at 6.9 grams-liter, a 28.9% reduction.

4. Chemical acid reduction - When I do this I use potbuttium bicarbonate. Each 0.9 grams-liter K bicarb. added will reduce acid by 1.0 grams-liter. You have to be careful when doing this because pH can rise too much. I first calculate how much acid I want to eliminate. Then I weigh up the amount of K bicarb. needed to neutralize the acid. I put a pH probe in the vat of wine and add the K bicarb. slowly, watching the pH. I stop K bicarb. addition before pH gets too high even if I cannot add all the K bicarb.

I used to grow Leon Millot, a cousin of Foch. In 2002 the starting acid was 9.0 grams-liter at harvest. I put a sample in the frig. overnight and another sample in the freezer. After warming the samples up the next day the acid tested at 7.8 and 5.0 grams-liter respectively. From those tests I knew I could reduce acid with pre fermentation cold soaking. I cold soaked the must for 7 days (excessive) at about 30F. This reduced the starting acid to 6.3 grams-liter.

Good luck!

Bill Frazier Olathe, Kansas USA